Which of the following methods should you use to implem…

You have an application consisting of a stateless web server tier running on Amazon EC2 instances behind load balancer,and are using Amazon RDS with read replicas. Which of the following methods should you use to implement a selfhealing and cost-effective architecture? (Choose two.)

A. Set up a third-party monitoring solution on a cluster of Amazon EC2 instances in order to emit custom CloudWatch metrics to trigger the termination of unhealthy Amazon EC2 instances.

B. Set up scripts on each Amazon EC2 instance to frequently send ICMP pings to the load balancer in order to determine which instance is unhealthy and replace it.

C. Set up an Auto Scaling group for the web server tier along with an Auto Scaling policy that uses the Amazon RDS DB CPU utilization CloudWatch metric to scale the instances.

D. Set up an Auto Scaling group for the web server tier along with an Auto Scaling policy that uses the Amazon EC2 CPU utilization CloudWatch metric to scale the instances.

E. Use a larger Amazon EC2 instance type for the web server tier and a larger DB instance type for the data storage layer to ensure that they don’t become unhealthy.

F. Set up an Auto Scaling group for the database tier along with an Auto Scaling policy that uses the Amazon RDS read replica lag CloudWatch metric to scale out the Amazon RDS read replicas.

Comments

Amazon RDS with read replicas is not High availability solution but scalability.
If you leave RDS like described in question, with read replicas only – than you don’t have high availability and you did not fulfill requirements set in question.
Even if A is right answer, you don’t need to use third-party monitoring solution to trigger termination of unhealthy EC2 instances when you can do same thing with CloudWatch.